1. Field of the Invention
The present invention relates to methods for making carbon nanotube arrays, particularly, to a method for making a high-density carbon nanotube array.
2. Discussion of Related Art
Carbon nanotubes (CNT) are a novel carbonaceous material and received a great deal of interest since the early 1990s. Carbon nanotubes have interesting and potentially useful electrical and mechanical properties. The conventional method for making carbon nanotube array includes arc discharge method, laser ablation method, and chemical vapor deposition (CVD) method.
Nowadays, the method for growing a CNT array on a substrate, such as a glass, silicon, or heat-resistant metal substrate, using the CVD method has matured. However, the density of the carbon nanotube array grown directly is restricted by the grown method of CVD, and the density cannot be regulated according to actual applications/uses. More so, the distance between the carbon nanotubes of the carbon nanotube array grown directly is several times of the diameter of the carbon nanotubes, and the maximal density of the carbon nanotube array is about 0.01 g/cm3 (gram/centimeter3). Thus the density of the carbon nanotube array grown directly is low and as a result, the properties of the carbon nanotube array such as heat conductive property, electricity conductive property cannot satisfy the actual applications/uses.
What is needed, therefore, is a simple method for making a high-density carbon nanotube array, and the carbon nanotubes in the carbon nanotube array are uniform and arranged in a preferred orientation.